Patent EA-002308-B1 (EA)
Title: Chloride assisted hydrometallurgical extraction of copper from sulphide ore materials
Inventor: JONES DAVID L
IPC: C22B3/06
Filed: 1998-08-14
Abstract: 1. A process for the extraction of copper from a sulphide copper ore or concentrate, comprising the steps of: subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halide and sulphate ions to obtain a resulting pressure oxidation slurry, subjecting the slurry to a liquid/solid separation step to obtain a resulting pressure oxidation filtrate and a solid residue containing an insoluble basic copper sulphate salt; leaching the basic copper sulphate salt produced by the pressure oxidation with an acidic sulphate solution to dissolve the basic copper salt to produce a leach liquor containing copper sulphate in solution and a resulting solid residue; separating the leach liquor from the solid residue; subjecting the leach liquor to a solvent extraction process to produce copper concentrate solution and a copper depleted raffinate; and recycling at least a portion of the raffinate to the pressure oxidation, characterized in that the raffinate is subjected to evaporation to remove water therefrom prior to the recycle thereof. 2. A process according to claim 1, wherein the evaporation is effected by means of a direct-fired evaporation process comprising the submerged combustion of a fuel in the raffinate being recycled. 3. The process according to claim 1, further comprising the steps of splitting the raffinate in at least two portions, wherein the one portion is recycled to the pressure oxidation and the other portion is recycled to the second leaching. 4. The process according to claim 1, further comprising the step of recycling the pressure oxidation filtrate to the pressure oxidation. 5. The process according to claim 4, further comprising the step of subjecting the pressure oxidation filtrate to evaporation to remove water therefrom prior to the recycle thereof to the pressure oxidation. 6. The process according to claim 5, wherein the evaporation is effected by means of a direct-fired evaporation process comprising the submerged combustion of a fuel in the filtrate being recycled. 7. A process according to claim 4, further comprising the steps of subjecting the pressure oxidation filtrate to a solvent extraction process, prior to the recycling of the filtrate, to produce a further copper concentrate solution and a further copper depleted raffinate which further copper depleted raffinate is recycled to the pressure oxidation. 8. The process according to claim 7, further comprising the step of subjecting the further copper depleted raffinate to neutralization prior to the recycling thereof to the pressure oxidation. 9. The process according to claim 1, wherein the pressure oxidation is carried out at a pH value of above about 2. 10. The process according to claim 9, wherein the pH in the pressure oxidation is from about 2.3 to about 3.8. 11. The process according to claim 1, wherein the second leaching is effected at a pH in the range of about 1.2 to about 2.2. 12. The process according to claim 11, wherein the pH in the second leaching is from about 1.5 to about 2.0. 13. The process according to claim 1, wherein the pressure oxidation slurry is flashed to atmospheric pressure at a temperature below the melting point of elemental sulphur. 14. The process according to claim l, wherein the halide is selected from chloride and bromide. 15. The process according to claim 1, wherein the copper concentration in the leach liquor is maintained at a value of from about 30 g/l to about 50 g/l. 16. The process according to claim 15, wherein the copper concentration in the leach liquor is maintained at a value of about 35 g/l.